Conventionally, there have been known portable electronic apparatuses constituted by a pair of casings coupled to each other, such that both the casings are provided with respective image display surfaces, thereby enabling both the image display surfaces to offer larger amounts of information to users (refer to Patent Documents 1 and 2).
Such portable electronic apparatuses are adapted, for example, to allow both the casings to move with respect to each other, between a single-surface exposed state (a full-closed state) where the pair of casings are overlaid on each other, a lower casing (a first casing) is covered at its image display surface (a first image display surface) with an upper casing (a second casing), and only an image display surface (a second image display surface) in the second casing is exposed, and a double-surface exposed state where the second casing has been moved with respect to the first casing, and the image display surfaces of both the casings are exposed.
In the double-surface exposed state, the second casing has been brought into a tilt state where the second image display surface is inclined with respect to the first image display surface at an angle of opening which is equal to or more than 90 degrees but less than 180 degrees (refer to Patent Document 1) or into a full-open state where the second image display surface is flushed with the first image display surface in the same plane (refer to Patent Document 2).